An indexable ball nose cutter

Abstract

The present invention relates to the field of milling cutters, and discloses an indexable ball-end cutter, which comprises a cutter body. A blade groove is provided on the cutter body, and a blade is installed in the blade groove. The blade includes a positive bottom surface, a reverse bottom surface and an inclined straight edge. A first straight cutting edge is connected to the high end of the inclined straight edge, and a second straight cutting edge is connected to the low end of the inclined straight edge. Arc cutting edges are respectively connected to the ends of the first straight cutting edge and the second straight cutting edge away from the inclined straight edge; the side wall of the blade groove includes an arc locking surface that fits with the side wall of the arc cutting edge of the blade, a straight locking surface that fits with the side wall of the inclined straight edge, and a bottom locking surface that fits with the bottom surface of the blade. The present invention can solve the defects existing in the existing ball-end cutters, such as waste of tool materials, unreliable installation, low positioning accuracy, or low utilization rate of the blade cutting edge, inconvenient installation and use, etc.

Description

Technical Field

[0001] The present invention relates to the field of milling cutters, and particularly to a indexable ball nose cutter. Background Art

[0002] In machining, especially when milling curved surfaces, ball nose cutters are usually used. For example, ball nose milling cutters with many different arc diameter series such as arcs of R8, R10, R20, etc. The main cutting edge part of this kind of cutter forms a ball shape after rotating around the cutter axis. Except for the integral ball nose cutter, most are hemispherical. In current indexable ball nose cutters, generally two or three inserts are installed on the corresponding cutter body. The cutting edges on each insert form a ball-shaped cutting edge line after rotation and overlap with the cutting edges of other inserts. There are currently various design schemes for this kind of ball nose cutter, but compared with the solution of this application, they all have defects such as waste of cutter material, unreliable installation, low positioning accuracy, or low utilization rate of the insert cutting edge, inconvenient installation and use.

[0003] As shown in Figure 1 and Figure 2 and Figure 3 are all common structural ways of ball nose cutters. The inserts are divided into left and right installations. The inserts that are not visible in the cutter are represented by dotted lines in the figures. It can be seen that Figure 1 there is only one circular arc cutting edge on the main cutting edge of the insert in . The other straight parts on the outer edge of the insert are used as the installation surface of the insert. This kind of insert can only be used for cutting on one side, resulting in low material utilization rate. Figure 2 In , the insert is willow leaf-shaped. In addition to the circular arc cutting edge, the insert also has a straight cutting edge. Each insert has two cutting edges. However, the installation and clamping surface of such an insert is often made under the straight edge and the circular arc edge. Especially the clamping surface under the circular arc edge, which is at the far end during the cutting use of the cutter. During the cutting process of the cutter, the clamping surface under the circular arc edge is difficult to provide a large enough locking force, and it is easy to loosen, resulting in premature failure of the cutter. In such a scheme, there is also a method of making one or two grooves on the bottom surface of the insert and relying on the protrusions made on the bottom surface of the cutter body to clamp the insert. However, the width and height of the groove are limited by the thickness of the insert, resulting in weak locking force and easy loosening. In addition, the long straight cutting edge is not used in actual cutting, causing a large waste of cutter material. Figure 3 In addition to having the Figure 2 disadvantages of the cutter in , the scheme also uses two inserts with different outer shapes and sizes on the left and right to combine. For such a cutter, the inserts on both sides cannot be interchanged, resulting in inconvenience in use and poorer economy. Summary of the Invention

[0004] The present invention aims to provide an indexable ball nose cutter to solve the problem that the existing ball nose cutter uses an arc-shaped abutting surface for locking and positioning, which is difficult to provide a sufficiently large locking force, resulting in loosening during use and causing tool failure.

[0005] To achieve the above object, the present invention adopts the following technical solution: An indexable ball nose cutter includes a tool body, a blade groove is provided on the tool body, a blade is installed in the blade groove, the blade includes a positive bottom surface, a reverse bottom surface and an inclined straight edge, a first straight cutting edge is connected to the high end of the inclined straight edge, a second straight cutting edge is connected to the low end of the inclined straight edge, and arc cutting edges are respectively connected to the ends of the first straight cutting edge and the second straight cutting edge away from the inclined straight edge; the side wall of the blade groove includes an arc locking surface that fits with the side wall of the arc cutting edge of the blade, a straight locking surface that fits with the side wall of the inclined straight edge, and a bottom locking surface that fits with the bottom surface of the blade.

[0006] The principle and advantages of this solution are as follows: In practical applications, the positive bottom surface and the reverse bottom surface are the two sides of the blade, and the inclined straight edge, the first straight cutting edge, the second straight cutting edge and the arc cutting edge are the outer contour edges of the blade. When installing the blade in this solution, the arc locking surface is in the part close to the axis of the tool body, and the straight locking surface catches the inclined straight edge of the blade at the far end. When the blade is under cutting force, the direction of the force is towards the central axis of the tool body. The arc locking surface can prevent the blade from moving towards the center of the tool body, while the straight locking surface can prevent the blade from rotating and disengaging from the blade groove.

[0007] Preferably, as an improvement, both the arc locking surface and the straight locking surface are perpendicular to the bottom locking surface. Since the peripheral abutting surface of the blade groove is perpendicular to the bottom surface, there is no need for excessive tool paths when machining these blade grooves, the tool body is simple to manufacture, and the installation accuracy of the blade is easier to guarantee.

[0008] Preferably, as an improvement, the positive bottom surface and the reverse bottom surface of the blade are parallel, and the side walls of the arc cutting edge, the straight cutting edge and the inclined straight edge of the blade are all perpendicular to the positive bottom surface and the reverse bottom surface. In this way, the blade structure is simple, the clearance angle of the blade is zero degree, the entire outer peripheral surface of the blade and the two bottom surfaces are perpendicular to each other, and it is very convenient to manufacture. The abutting surface between the blade and the blade groove is composed of the flank face of the non-working cutting edge, the straight edge face and one bottom surface of the blade, corresponding to each locking surface on the blade groove respectively. The abutting and locking effect between the blade and the blade groove is better, and the blade clamping is more stable and reliable.

[0009] Preferably, as an improvement, the arc-shaped edge includes a long arc-shaped edge whose end is tangentially connected to the first straight edge and a short arc-shaped edge whose end is tangentially connected to the second straight edge. When observed from the orthographic projection of the bottom surface, the starting points of the long arc-shaped edge and the short arc-shaped edge intersect; the long arc-shaped edge and the first straight edge form the long edge of the blade, and the length of the first straight edge is less than or equal to 15% of the length of the long edge; the short arc-shaped edge and the second straight edge form the short edge of the blade, and the length of the second straight edge is less than or equal to 20% of the length of the short edge. In this way, the main part of the blade edge is an arc-shaped edge, without waste. Compared with the past ball-end cutter scheme, under the same usage conditions, it is smaller and more material-saving for the blade.

[0010] Preferably, as an improvement, the long edge forms a long cutting edge on one side of the positive bottom surface of the blade, and a long chip-breaking groove is provided between the long cutting edge and the positive bottom surface; the short edge forms a short cutting edge on one side of the reverse bottom surface of the blade, and a short chip-breaking groove is provided between the short cutting edge and the reverse bottom surface. In this way, there is only one cutting edge and one chip-breaking groove on any bottom surface of the blade, reducing the processing difficulty around the blade and making the blade easier to manufacture.

[0011] Preferably, as an improvement, in the thickness direction of the blade, the height of any point on the long cutting edge does not exceed the height of the positive bottom surface, and the height of any point on the short cutting edge does not exceed the height of the reverse bottom surface. In this way, the locking and clamping of the blade and the blade groove are more stable.

[0012] Preferably, as an improvement, in the thickness direction of the blade, both the long cutting edge and the short cutting edge are curved, and the number of points with the same height on the cutting edge lines of the long cutting edge and the short cutting edge is less than or equal to two. In this way, when the cutting edge of the blade participates in cutting, the entire cutting edge will not cut into the workpiece simultaneously, the cutting force borne by the blade is relatively small, and the service life of the blade is longer.

[0013] Preferably, as an improvement, the angle between the first straight edge and the inclined straight edge is less than 90°, and the angle between the second straight edge and the inclined straight edge is greater than 90°. In this way, the overall contour of the blade is in the shape of a human eye, the blade is asymmetric when viewed from the direction facing the bottom surface, the overall volume of the blade is significantly reduced compared with the prior art, and the utilization rate of the blade material is higher under the same cutting edge range.

[0014] Preferably, as an improvement, two blade grooves are asymmetrically provided on the tool body. The two blade grooves are respectively the same as the front contour and the reverse contour of the blade. Blades are respectively installed on the front and the reverse sides in the two blade grooves. For the blade installed on the front side, its long cutting edge is the working cutting edge, and the starting point of the cutting edge near the conductor rotation axis is located on the rotation center of the whole tool; for the blade installed on the reverse side, its short cutting edge is the working cutting edge, and the starting point of the cutting edge near the tool body rotation axis is located outside the rotation center of the whole tool. In this way, the two identical blades can be used in a indexable manner in the two blade grooves, and each blade can be used indexably twice, with high tool material utilization rate and cutting edge utilization rate.

[0015] Preferably, as an improvement, the working cutting edge protrudes outside the tool body. After the tool body rotates, the cutting edge line of the working cutting edge envelopes to form a rotating surface which is a complete hemispherical surface and a cylindrical surface tangent to it. The cutting edge line does not coincide with any generatrix of the rotating surface on the rotating surface, and the end point of the working cutting edge exceeds half of the spherical body of the whole rotating surface. In this way, all parts of the corresponding flank face of each cutting edge are located inside this rotating surface, and the cutting edge line rotating surface does not interfere with any other position of the blade or the tool body. The tool is more brisk during the machining process, and the surface finish of the machined workpiece is better.

[0016] The solution of this application has the following technical advantages compared with various past ball-end cutter solutions:

[0017] 1. The blade structure is simple. The clearance angle of the cutting edge of the blade is zero degree. The whole outer peripheral surface of the blade and the two bottom surfaces are perpendicular to each other. There is only one chip-breaking groove on each bottom surface, which is very convenient for manufacturing. In the past, the clearance angle of this type of blade was generally between 7 and 20 degrees. It was not easy to ensure the sharp state of the cutting edge when pressing the blank or grinding the cutting edge during manufacturing. Moreover, due to its zero clearance angle, the blade in this solution has stronger support for the cutting edge compared with the blade with a non-zero clearance angle, and the strength of the cutting edge part is relatively much better. The single-sided single chip-breaking groove makes the peripheral machining of the whole blade easier.

[0018] 2. The blade has two cutting edges, and the main parts are all arc cutting edges without waste parts. Compared with the past ball-end cutter solutions, under the same usage conditions, it is smaller and more material-saving for the blade. For example, compared with the R10mm ball-end blade with the same blade thickness, this solution can save at least 25% of the blank material. Compared with the R8mm ball-end blade with the same blade thickness, it can save at least 40% of the blank material. For those ball-end blades with only one cutting edge, this solution has even greater economic benefits in terms of efficiency.

[0019] 3. The blade in this solution is firmly installed. Except that Figure 1 the single-edge blade can have a relatively stable installation structure, Figure 2 、 Figure 3There are defects in the theory of installation and fastening. Since the arc-shaped abutment surface of the blade fits the cutter body at the far end, the cutting force makes the blade tend to rotate outward when the blade is cutting. Those skilled in the art know that the relative sliding, that is, the freedom of rotation, cannot be restricted between the two closely attached arc-shaped surfaces. It is precisely the outer side of the blade that does not block its structure, so it is difficult to achieve a stable installation in theory. Even if some blade solutions make a slot on the bottom surface of the blade to prevent it from rotating, the height of the slot is limited by the thickness of the blade and cannot be very high or very large. The height of the slot can only be about 1 / 3 of the thickness of the blade at most, which limits the size of the blade locking force. According to the principle of lever effect, it is not easy to lock the blade, and the corresponding raised abutment surface on the cutter body will not be very large. Since the cutting force of the tool is very large when it is cutting, it will soon wear and deform after being used for a period of time, resulting in the blade being installed loosely and losing installation accuracy. When the blade is installed in this solution, the arc locking surface is located near the axis of the cutter body, while the linear locking surface clamps the blade at the far end, so that when the blade is subjected to cutting force, the force is directed toward the center axis of the cutter body. The arc locking surface can prevent the blade from moving toward the center of the cutter body, while the linear locking surface can prevent the blade from rotating out of the blade slot. In addition, the height of the locking surface of the blade in this solution is almost the same as the height of the blade itself, which can ensure that the blade can be fully wrapped and firmly installed.

[0020] 4. The tool body is simple to manufacture. Since the peripheral locking surface and the bottom surface of the blade slot are in a vertical relationship, there is no need for too many tool paths when processing these blade slots, and the blade installation accuracy is easier to ensure.

[0021] 5. When the blade of this scheme is in use, the blade edge line does not overlap with any ball head rotating surface, which ensures that when the blade edges are involved in cutting, not all of the cutting edges will cut into the workpiece at the same time. The cutting edge that first cuts into the workpiece will also leave the workpiece first, and the cutting edge that cuts in later will leave later. In this way, the cutting force borne by the blade is relatively small, making the tool lighter in the entire processing process, and can greatly extend the service life of the blade and the tool body. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of an existing ball-end tool in the background technology of the present invention.

[0023] Figure 2 It is a schematic structural diagram of an existing ball-end tool in the background technology of the present invention.

[0024] Figure 3 It is a schematic structural diagram of an existing ball-end tool in the background technology of the present invention.

[0025] Figure 4 It is a front view of the bottom surface of the blade in the embodiment of the present invention.

[0026] Figure 5 Front view of the back bottom surface of the blade in the embodiment of the present invention.

[0027] Figure 6 is Figure 4 right view of.

[0028] Figure 7 Axonometric view of the front bottom surface of the blade in the embodiment of the present invention.

[0029] Figure 8 Axonometric view of the back bottom surface of the blade in the embodiment of the present invention.

[0030] Figure 9 Exploded view of the front installation of the blade in the blade groove in the embodiment of the present invention.

[0031] Figure 10 Exploded view of the back installation of the blade in the blade groove in the embodiment of the present invention.

[0032] Figure 11 Assembly drawing of the front installation of the blade in the blade groove in the embodiment of the present invention.

[0033] Figure 12 Assembly drawing of the back installation of the blade in the blade groove in the embodiment of the present invention. Detailed implementation manners

[0034] The following is further detailed through specific implementation manners:

[0035] The reference numerals in the drawings of the specification include: tool body DT, screw LD, front bottom surface D1, back bottom surface D2, inclined straight edge C, first straight cutting edge F, long arc cutting edge A, second straight cutting edge E, short arc cutting edge B, starting point H, long arc flank A1, short arc flank B1, first straight flank F1, second straight flank E1, straight end face C1, long rake face A2, short rake face B2, long arc locking face A1', straight positive locking face C1', positive bottom locking face D2', short arc locking face B1', reverse straight locking face C2', reverse bottom locking face D1'.

[0036] Embodiment: A indexable ball nose cutter, as Figure 11 , Figure 12 shown, includes a tool body DT, a blade groove is provided on the tool body DT, and a blade is connected in the blade groove. As Figure 4 , Figure 5As shown, a mounting hole is provided in the middle of the blade. The mounting hole is a double-sided countersunk hole. The blade includes a positive bottom surface D1, a reverse bottom surface D2, and an inclined straight edge C. A first straight cutting edge F is connected to the high end of the inclined straight edge C. The angle between the first straight cutting edge F and the inclined straight edge C is less than 90°. A second straight cutting edge E is connected to the low end of the inclined straight edge C. The angle between the second straight cutting edge E and the inclined straight edge C is greater than 90°. Arc cutting edges are respectively connected to the ends of the first straight cutting edge F and the second straight cutting edge E away from the inclined straight edge C. The arc cutting edges include a long arc cutting edge A whose end is tangentially connected to the first straight cutting edge F and a short arc cutting edge B whose end is tangentially connected to the second straight cutting edge E. The long arc cutting edge A and the short arc cutting edge B have the same starting point H in the orthographic projection contour.

[0037] As Figure 6 shown, the positive bottom surface D1 and the reverse bottom surface D2 of the blade are parallel. As Figure 7 , Figure 8 shown, the side wall of the blade includes a long arc flank A1 corresponding to the long arc cutting edge A, a short arc flank B1 corresponding to the short arc cutting edge B, a first straight flank F1 corresponding to the first straight cutting edge F, a second straight flank E1 corresponding to the second straight cutting edge E, and a straight end face C1 corresponding to the inclined straight edge C. The long arc flank A1, the short arc flank B1, the first straight flank F1, the second straight flank E1, and the straight end face C1 are all perpendicular to the positive bottom surface D1 and the reverse bottom surface D2.

[0038] The long arc cutting edge A and the first straight cutting edge F form the long cutting edge of the blade. The length of the first straight cutting edge F is less than or equal to 15% of the length of the long cutting edge; the short arc cutting edge B and the second straight cutting edge E form the short cutting edge of the blade. The length of the second straight cutting edge E is less than or equal to 20% of the length of the short cutting edge. As Figure 7 shown, the long cutting edge forms a long cutting edge on the side of the positive bottom surface D1 of the blade. A long chip-breaking groove is provided between the long cutting edge and the positive bottom surface D1. The groove surface of the long chip-breaking groove is a long rake face A2 corresponding to the long cutting edge. As Figure 8 shown, the short cutting edge forms a short cutting edge on the side of the reverse bottom surface D2 of the blade. A short chip-breaking groove is provided between the short cutting edge and the reverse bottom surface D2. The groove surface of the short chip-breaking groove is a short rake face B2 corresponding to the short cutting edge.

[0039] As Figure 6 shown, in the thickness direction of the blade, the height of any point on the long cutting edge does not exceed the height of the positive bottom surface D1, and the height of any point on the short cutting edge does not exceed the height of the reverse bottom surface D2. In the thickness direction of the blade, both the long cutting edge and the short cutting edge are curved, and the number of points with the same height on the cutting edge lines of the long cutting edge and the short cutting edge is less than or equal to two.

[0040] Combined with Figure 9 , Figure 10As shown in the figure, there are two asymmetric blade grooves on the tool body DT. The two blade grooves are respectively the same as the front contour and the reverse contour of the blade. Blades are installed on the front and reverse sides of the two blade grooves respectively through screws LD. For the blade groove with the blade installed on the front side, its side wall includes a short arc locking surface B1' that fits the short arc flank B1 of the blade, a positive straight locking surface C1' that fits the straight end face C1, and a positive bottom locking surface D2' that fits the reverse bottom surface D2 of the blade. The short arc locking surface B1' is divided into two unconnected segments, but they belong to the same arc surface. The heights of the short arc locking surface B1' and the positive straight locking surface C1' are the same as the blade thickness, and both the short arc locking surface B1' and the positive straight locking surface C1' are perpendicular to the positive bottom locking surface D2'. For the blade groove with the blade installed on the reverse side, its side wall includes a long arc locking surface A1' that fits the long arc flank A1 of the blade, a reverse straight locking surface C2' that fits the straight end face C1, and a reverse bottom locking surface D1' that fits the positive bottom surface D1 of the blade. The long arc locking surface A1' is divided into two unconnected segments, but they belong to the same arc surface. The heights of the long arc locking surface A1' and the reverse straight locking surface C2' are the same as the blade thickness, and both the long arc locking surface A1' and the reverse straight locking surface C2' are perpendicular to the reverse bottom locking surface D1'. The first straight flank F1 and the second straight flank E1 on the blade do not participate in the locking of the blade.

[0041] Combined with Figure 11 , Figure 12 As shown in the figure, for the blade installed on the front side, its long cutting edge is the working cutting edge, and the starting point H of the cutting edge near the conductor rotation axis is located at the rotation center of the entire tool; for the blade installed on the reverse side, its short cutting edge is the working cutting edge, and the starting point H of the cutting edge near the rotation axis of the tool body DT is located outside the rotation center of the entire tool. The working cutting edge protrudes outside the tool body DT. After the tool body DT rotates, the rotation surface formed by the envelope of the cutting edge line of the working cutting edge is a complete hemispherical surface and a cylindrical surface tangent to it. The cutting edge line does not coincide with any generatrix of the rotation surface on the rotation surface, and the end point of the working cutting edge exceeds half of the spherical body of the entire rotation surface.

[0042] The above are only embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well known in the art are not described in detail here. It should be noted that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to explain the content of the claims.

Claims

1. A indexable ball nose cutter, comprising a cutter body, on which a blade groove is provided, and a blade is installed in the blade groove, Characterized in that: The blade includes a positive bottom surface, a reverse bottom surface and an inclined straight edge. The high end of the inclined straight edge is connected with a first straight cutting edge, and the low end of the inclined straight edge is connected with a second straight cutting edge. One ends of the first straight cutting edge and the second straight cutting edge far away from the inclined straight edge are respectively connected with an arc cutting edge; the side wall of the blade groove includes an arc locking surface that fits with the side wall of the arc cutting edge of the blade, a straight locking surface that fits with the side wall of the inclined straight edge, and a bottom locking surface that fits with the bottom surface of the blade; the arc cutting edge includes a long arc cutting edge whose end point is tangentially connected with the first straight cutting edge, and a short arc cutting edge whose end point is tangentially connected with the second straight cutting edge. In the bottom surface orthographic projection contour, the starting points of the long arc cutting edge and the short arc cutting edge intersect; the long arc cutting edge and the first straight cutting edge form the long cutting edge of the blade, and the length of the first straight cutting edge is less than or equal to 15% of the length of the long cutting edge; the short arc cutting edge and the second straight cutting edge form the short cutting edge of the blade, and the length of the second straight cutting edge is less than or equal to 20% of the length of the short cutting edge.

2. The indexable ball nose cutter according to claim 1, Characterized in that: The arc locking surface and the straight locking surface are both perpendicular to the bottom locking surface.

3. The indexable ball nose cutter according to claim 1, Characterized in that: The positive bottom surface and the reverse bottom surface of the blade are parallel, and the side walls of the arc cutting edge, the straight cutting edge and the inclined straight edge of the blade are all perpendicular to the positive bottom surface and the reverse bottom surface.

4. The indexable ball nose cutter according to claim 1, Characterized in that: The long cutting edge forms a long cutting edge on the positive bottom surface side of the blade, and a long chip breaker groove is provided between the long cutting edge and the positive bottom surface. The short cutting edge forms a short cutting edge on the reverse bottom surface side of the blade, and a short chip breaker groove is provided between the short cutting edge and the reverse bottom surface.

5. The indexable ball nose cutter according to claim 4, Characterized in that: In the thickness direction of the blade, the height of any point on the long cutting edge does not exceed the height of the positive bottom surface, and the height of any point on the short cutting edge does not exceed the height of the reverse bottom surface.

6. The indexable ball nose cutter according to claim 5, Characterized in that: In the thickness direction of the blade, both the long cutting edge and the short cutting edge are curved, and the number of points with the same height on the cutting edge lines of the long cutting edge and the short cutting edge is less than or equal to two.

7. The indexable ball nose cutter according to claim 6, Characterized in that: The included angle between the first straight cutting edge and the inclined straight edge is less than 90°, and the included angle between the second straight cutting edge and the inclined straight edge is greater than 90°.

8. The indexable ball nose cutter according to claim 7, Characterized in that: Two blade grooves are asymmetrically provided on the cutter body. The two blade grooves are respectively the same as the front contour and the reverse contour of the blade. Blades are respectively installed on the front and the reverse of the two blade grooves. For the blade installed on the front, its long cutting edge is the working cutting edge, and the starting point of the cutting edge near the conductor rotation axis is located on the rotation center of the whole cutter; for the blade installed on the reverse, its short cutting edge is the working cutting edge, and the starting point of the cutting edge near the cutter body rotation axis is located outside the rotation center of the whole cutter.

9. A indexable ball nose cutter according to claim 8, characterized in that: The working cutting edge protrudes outside the cutter body. After the cutter body rotates, the cutting edge line of the working cutting edge includes a complete hemispherical surface formed by the rotating surface and a cylindrical surface tangent thereto. The cutting edge line does not coincide with any generatrix of the rotating surface on the rotating surface, and the end point of the working cutting edge exceeds half of the sphere of the entire rotating surface.

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